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Carry out the Investigating how gel electrophoresis is used to separate DNA fragments of different lengths. experiment referring to the Teaching Pack for lesson plans and resources.
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In this task, learners follow instructions to carry out gel electrophoresis to identify the genotype of different people for a specific gene. As part of this task, learners undertake a circus of activities associated with gel electrophoresis and analyse a gel to draw conclusions. Additional animations can further support this activity, such as:
https://learn.genetics.utah.edu/content/labs/gel/ www.medicine.mcgill.ca/physio/vlab/Other_exps/endo/electrophoresis.htm, www.sumanasinc.com/webcontent/animations/content/pcr.html
Learners match a series of key terms to definitions (taken from Topic 6) that concern the structure of DNA and RNA. Words will include specific, complementary and hybridisation. (F)
Learners work in pairs to undertake an activity focusing on the analysis of the stages of genetic engineering. Provide each learner with an image showing one of the steps undertaken in the process of genetic engineering. Also provide each learner with a piece of blank paper. Each learner takes it in turn to describe the image to their partner using only spoken words (they cannot sketch or use hand signals). Their partner is expected to reproduce the diagram during the description and then both learners discuss what it shows. (I)
The process of genetic engineering is often explained by using analogy (e.g. the genetic engineer’s ‘toolkit’). It can be of great help to learners to think that the process consists of ‘tools’. Examples include restriction enzymes being represented as scissors, and glue acting as DNA ligase. Animations that use analogies:
www.dnaftb.org/ http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120078/bio37.swf::Restriction%20Endonucleases http://higheredbcs.wiley.com/legacy/college/voet/0470129301/animated_figs/ch03/3-26.html (I)
Learners compare and contrast cellular DNA replication during the cell cycle with the process of PCR. Provide a list of characteristics of each process to each learner. Learners consider the similarities and the differences between them by cutting out the statements, mixing them up and then sticking the characteristics on a large sheet of paper to re-create the table. To assess understanding, learners prepare a piece of paper that has ‘DNA replication’ on one side, and ‘PCR’ on the other. They hold up the correct side to show you when you call out a statement. (I)
Provide opportunities for learners to undertake calculations related to the process of PCR. The three stages of PCR are repeated n times, giving 2n copies of the original DNA. Learners calculate the number of molecules of DNA produced from one double-stranded starting molecule, after a given number of cycles. This would be an excellent opportunity to use mini-whiteboards with learners so that you can immediately see who is able to calculate the figures accurately, and who needs further support. (F)
Support learners as they explore a database associated with bioinformatics, such as Ensembl (genome), GenBank (DNA sequence), UniProt (protein sequence), PDB (protein structure) and COSMIC (somatic mutations in cancer). Provide an opportunity for learners to compare the primary sequence of a protein common to a wide range of organisms (e.g. ribonuclease, cytochrome c-oxidase, or others). Learners compare the number and sequence of amino acids and comment on the similarities and differences. This is an opportunity to revisit the nature of some amino acids (which ones can form disulfide bonds), which they encountered in Topic 2, and to suggest the evolutionary relationships between them. The following is a useful source of lesson ideas:
www.bioinformaticaindeklas.nl/en/
Learners explore the new technique of CRISPR/CAS9-dependent gene editing by carrying out research to write a newspaper article for a general (non-scientific) audience. The challenge is for them to describe and explain the procedure in simple terms, but with sufficient detail and scientifically accurate. Encourage learners to show their work to their family or friends who may not study biology. (I)
Learners make a model microarray using items of rubbish (e.g. empty food packets, cardboard, paper, etc.). They then take it in turns to explain to you how this gene technology works with reference to sources they have found in their textbook or online.
Many of the procedures listed in the syllabus in this chapter require learners to recall the series of steps that are undertaken when carrying them out in the laboratory. Support learners to produce a clear summary set of notes on this topic, perhaps by asking them to complete a series of missing-word boxes in a flow diagram, or arranging a series of numbered statements into the correct order. (F)
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